Skin irritability to sodium lauryl sulphate--as measured by skin water vapour loss-by sex and race.

The skin irritability of 38 volunteers (23 males, 15 females), of different ethnic groups, to sodium lauryl sulphate, 2% aqueous, was studied by measurement of skin water vapour loss (SVL). The mean SVL values of unirritated skin of females (2.9 g water/m/h) was significantly lower than males (5.5 g water/m2/h) (P-<0.001); the mean values between the different ethnic groups were not significantly different, The mean SVL values of irritated skin of males and females were not significantly different; the values for Chinese were significantly higher than Malays (p<0.05), but not significantly different between Chinese and Indians and between Malays and Indians. The irritation index (which is defined as the difference of SVL value between irritated and unirritated skin over SVL value of unirritated skin) was significantly lower in males (4.6 g water/m2/h) than females (12.4 g water/m2/h) (P<.01). It was not significantly different between the various ethnic groups. It appears that the skin irritability (to SLS 2% aqueous) of males and females differ. Female skin appeared to be more irritable compared to male skin. The skin irritability of different ethnic groups appeared the same.